Method of testing flour as to color and ash content



Sept. 2, 1941. E. BAUER 2,255,034v

METHOD OF TESTING FLOUR AS T0 COLOR AND ASH CONTENT Filed Nov. 16; 1938g 7//f/// i jg! a@ l 4f J 19 a 10 w y /L w. d jzga- 3 /v/.jg 30.

Patented Sept. 2, 1941 METHOD oF TESTING FLoUn. As To coLoR AND AsnCONTENT Edwin Bauer, Berlin, Germany Application November 16, 1938,Serial No. 240,874 In Germany November 16,1937

1 Claim.

The present invention relates to a method of determining to what degreea flour has been ground or of ascertaining the amount of scale presentin the flour to be tested.

The scale content of a our can be determined from the ash content of thesame. When, for instance, a certain amount of flour is burnt at about950 C. an ash is left, which contains the non-combustible constituentsof the grain. These non-combustible constituents chiefly consist ofminerals, of which by far the greater part originates from the scale,and only a very little part originates from the interior of the grain.Whilst the part of non-combustible minerals, i. e. the ash content, ofthe our proper only amounts to about 0.35%, the scale tissue may containup to 6 or 7% of non-combustible mineral constituents. If after acombustion the percentage of ash left is very high, this shows that theflourtested contains a great amount of constituents from the scaletissue and therefore is very rich in scale substance. If a flour is verydark, it contains a very high percentage of scale substance. fore alsobe determined by a color comparison. Light flours are poor in ashes anddark flours are rich in ashes. Therefore, iiours which are poor in ashesoriginate from the interior of the grain and flours which are rich inashes from the scale. k

Of the methods of testing flour hitherto known the most exact consistsin determining the ash of fire-proof brick-work, in the interior ofwhich a temperature of SOO-920 C. is maintained. In the'course of 60-90minutes the flour will burn -to a white ash. After the ash for about anhour has been placed in a receptacle with a waterbinding filling the ashis weighed. The weight shows the ash content of thetested flour.

Since the described method is very complicated, many attempts have beenmade to determine the ash content directly from the color of the our.One of the methods proposed is the so-called `Pekar water test,according to which the flour tobe tested and the sample of our used forcomparison after a preliminary-treatment are examined through theinspection open- The ash content can there' ing of the test plate. Sucha test comparison is however of little use, because the result of it isdependent upon a subjective impression.

Another attempt to replace the ash test by another test method was thefollowing process: Of the flour to be tested a flour-Water mixture wasprepared and a layer of a definite height of this mass or pap was placedin an apparatus between a source of light and a light-sensitive cell,which was connected to a measuring instrument. When the source of lightwas switched on the light-sensitive cell was excited by the light rayspenetrating the flour-Water mixture.

The intensity of the light acting upon the cell was hereby dependentupon the color of the mixture. The tests made according tothis methodwere however not satisfactory. The reason for this unsatisfactory resultwas thought to bethat the our was in moist state when it was penetratedby the light rays. l,

According to the present invention the drawbacks described above areavoided. The essential features of the new method are that the lightrays are sentthrough a layer of our in dry state and that the intensityof the penetrating light rays is measured by means of a calibratedinstrument. An amount of the our to be tested of an accuratelydetermined Weight 1s in a dosing device compressed until a layer of apredetermined height is lobtained. The

height of the layer always 'remains the same. The volume of the dosingdevice can be altered, and it is therefore also .possible totest-flours, which have a high content of scale substances, yand theheight of the layer of which before the compression is greater than thatof flours having a. low content of scale substances.- The said dosingdevice consists of an innerv annular sleeve with a glass cover and asecond outer annular sleeve, which is equipped with a removable glasscover. By means of pins, which are fixed to the inner surface of theouter sleeve and are slidable in helical grooves in the inner sleeve,the latter can be moved telescopically Within the former. The dosing andthe forming of a layer of the desired height take place between theglass covers of the described sleeves. The test of the flour in thedosing device by means of light rays is performed in a specialapparatus, lin which the light rays from a source of light and heatafter the penetration of the compressed flour are projected against aphotoelectric cell. Through the heat which thereby is developed themoisture is simultaneously driven out. The photo-electric cell isconnected to a continuous current measuring instrument, the

in which scale of which is so graduated and calibrated that the pointerin each case indicates the ash Acontent or the shade of color of theflour which is tested. Since the purev iiour has a constant ash conte'ntor content of minerals in the form of protoxide of potassium andphosphoric acid, the coloris altered through the presence of fragmentsof scale, vwhich together with the germs are the carriers of the mineralsubstances. Due to this, the more the corn is ground out the more thecontent. of vscale and germ substance and incidentally the ash contentor shade of color will increase. 'I'he mineral constituents in -theiiour, the amount of which is dependent upon the degree to which theiiour is ground out, will, when the light rays penetrate the layer offlour, which always has the same weight and the same height,

in a manner known per se, for instance by means offer a higher or lowerresistance against the rays, whereby a correspondingly weaker orstronger current is generated in the photo-elecmethod according to theinvention is illustrated f by way of example in the accompanying drawingFig. 1 is a vertical section through a testing apparatus with inserteddosing device.

. Fig. 2 is a lateral view of the dosing device. Fig. 3 shows the dosingdevice in plan view. Fig. 4 is a section through the dosing device onthe line 4-4 in Fig. 3. I

Fig. 5 shows the device by means of which the surface of the layer ofour is smoothed.

The testing apparatus consists of a box of rectangular cross-section, inthe upperA part of` sired, a suitable lens or other ray condenser may bearranged between the lamp 2 andthe cell 6.

. The cell 6 is, through wires 3 and 9, connected vto a continuouscurrent meter 1. In conformity with the strength of the currentgenerated in the cell the pointer of the instrument is deflected and onthe scale ||I indicates the ash content or the shade of color of theflour in each case.

Figs. 2, 3, and 4 show thedevice in which the flour is dosed andcompressed until a layer of the r desired height is obtained. In Fig. 223 denotes the outer sleeve on which a removable glass cover 24 isarranged. To the outer surface of this rounding the removable glasscover 24 projections 32 are provided, which, when the sleeve is turned,will engage the lower side ofthe handle 30 and a tongue 3| arrangeddiametrically opposite the same.

The apparatus acts in the following manner:

The inner sleeve 2| of the dosing device, which when the ring 29 isturned is raised and lowered telescopically, is brought into itslowermost position. Thereupon the glass cover 24 of the outer sleeve isremoved, and the iiourto be tested is filled in. preferably through afilter, whereupon the surface of the charge of our is stroked level ofthe smoothing device I6 shown in Fig. 5. After the excess of fiour hasbeen stroked off the filled dosing device is weighed. If it is foundthat the dosing device contains, for instance, more than 3 grammes ofthe our to be tested, the inner sleeve 2| is, by means of .the ring 29,turned somewhat to the right, whereby the volume of the hollow space ofthe dosing device between the glass covers is reduced. A small amount offlour is again removed by means of the smoothing device |6 and thedosing device is again weighed. If it is now found that the dosingdevice contains less than 3 grammes of flour, the inner sleeve is turnedto the left, whereby the volume of thev 'hollow space within the same inincreased. An

additional amount of our is supplied and the surface of the charge offlour is again stroked level. 'Ihis procedure is repeated until thedesired weight of 3 grammes is obtained. 'I'he glass cover 24 isthereuponfplaced upon the outer sleeve 23 and turned until theprojections 32 engage the handle 30 and the lug 3|. Finally the innersleeve 2| is turned to the right until the ring 29 abuts against thelower edge of the outer sleeve 23. In this Way the layer of flour in thedosing device of the prescribed weight is always so compressed that theheight of the layer of flour is `kept constant. Now the dosing devicewith the flour to be tested ispushed 'into the apparatus through theopening 20 between the sleeve pins 25 and 26 are iixed, which areslidable in slots 21 and 28 in the inner sleeve 2|.

Fig. 4 shows the inner sleeve 2| in its uppermost position. As it willbeseen from the draw-y ing the 'grooved ring or flange 29 of the innersleeve 2| abuts against the lower edge of the outer sleeve 23 whensleeve 23 is in its lowermost position. By means of the handle 30 on theouter sleeve 23 the device may be held with one hand, whilst the innersleeve 2| is turned with the other hand. 0n the bottom side of the rimsurlamp.2 and the cell 6. After the lamp has been switched on thepointer of the measuring instrument will ascend until the moisture inthe flour has been driven out. When the pointer iinally stops ata valueon the scale, which is only de- -pendent upon the ash content of theiiour, the

result is read.

I claim: l The method of determining the ash content of fleurs,comprising the steps of compressing a predetermined quantity'of flourcontaining moisture in a dosing, device, supporting the compressediiourbetween a near source of light and heat and a photo-electricmeasuring device until the indicator of the device reaches a finalposition, measuring from the final positionof the indicator of thephoto-electric device the light transmitted through said iiour, andcomparing the measurement obtained with similarv measurements of sampleshaving the same weight, thickness and volume and containing knownquantities of ash.

EDWIN BAUER.

